1. Field of the Invention
The present invention relates to a technology for attaching an external device to a main apparatus using an electric cable.
2. Description of the Related Art
In an electronic apparatus such as an image forming apparatus, an optional device is typically attached to a main unit for enhancing functions of the main unit. For example, a composite machine is an image forming apparatus that has functions of a copier, a printer, and a fax machine. A composite machine shown in FIGS. 15A and 15B includes an image reading unit 2 (optional device) mounted on an imaging device 1 (main unit). An operation section 3 protrudes from the front side of the image reading unit 2. A reading unit of the image reading unit 2 is located in a casing member 4, and the casing member 4 is covered by an external cover 5.
Electric cables 6a, 6b, 6c extend out from the reading unit, pass through a space 7 between the casing member 4 and the external cover 5, and connect to the imaging device 1, in such a manner not to cross over each other. As shown in FIG. 16, the electric cables 6a, 6b, 6c are electrically connected to electrical substrates a, b, c in the imaging device 1, respectively.
Different optional devices can be provided according to a user's requirement. For example, when a user orders a composite machine, the imaging device 1 and the image reading unit 2 are provided. When a user orders a printer, only the imaging device 1 is provided, and when a user orders a fax machine or a copier, the imaging device 1, the image reading unit 2, and a corresponding circuit board are provided.
The main unit and the optional device are not always provided integrally. According to a user's requirement, the optional device can be an external device that is attached to the main unit with electric cables, and located separately.
For example, as shown in FIG. 17, the image reading unit 2 is placed on a table 8, and is electrically connected to the imaging device 1 with electric cables 6d, 6e, and 6f. Accordingly, the operation section 3 is situated at a lower level as compared to the case when the image reading unit 2 is mounted on the imaging device 1. This makes it easy for anyone to operate the image reading unit 2, thus improving convenience.
Japanese Patent Application Laid Open No. 2002-101242 and Japanese Patent Application Laid Open No. 2000-131909 disclose examples of the conventional technology.
However, in the conventional electronic apparatus, the optimal lengths of each electric cable 6d, 6e, and 6f differ, depending on how the imaging device 1 and the image reading unit 2 placed on the table 8 are located. In the example shown in FIG. 18, the electric cable 6f is not long enough that it is stretched along the imaging device 1. On the other hand, the electric cables 6d, 6e are too long that they hang down. Accordingly, the electric cables can impair safety or spoil the appearance of the electronic apparatus.